Accurate geographic tracking of mobile devices

ABSTRACT

A tracking system is described having at least two mobile transmitter/receivers (“transceivers”) which sense and respond to at least one tracking transceiver. The signals sent to and received from the mobile transceivers are analyzed to get a distance (range) that each is from the tracking transceiver. This can be converted into a position relative to the mobile transceivers. If there are enough transceivers, and at least one knows its absolute location, the absolute location of the mobile transceivers may be determined. Existing smartphones, cellphones, Wi-Fi routers, Bluetooth devices, and near-field devices that have on-board processors, can be modified to run executable code to implement the current invention. They may communicate using at least one of the modalities for tracking. These may be implemented in tracking the position and orientation of moving devices, such as a head-mounted display for virtual/Augmented Reality, automobiles, packages in a package delivery truck. The system may also be implemented to identify and keep track of the last known location of various objects.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to co-pending U.S.provisional application No. 62/115,954, filed Feb. 13, 2015, entitled“Utilizing Radio Frequency Signals Transmitted by Stationary or MobileDevices for Accurate and Geographically Broad Tracking of Mobile Devicesin the Real World, Augmented Reality or Virtual Reality”, the entiretyof which is incorporated by reference herein.

BACKGROUND

1. Field of Invention

The present invention relates to a system for tracking of the positionof multiple objects utilizing radio frequency (RF) transmitters, andmore specifically to a highly accurate system for tracking the positionof multiple objects that may be implemented indoors.

2. Description of Related Art

Determining the position of an electronic device or object has been asubject of much research since the emergence of RADAR and SONAR. Avariety of proximity and position detection schemes exists today. Forexample, the Global Positioning System (GPS) has been transformationalto military and civilian users by providing a system of orbitingsatellites that have highly synchronized clocks emitting timinginformation continuously. A GPS receiver obtaining signals from threesatellites can triangulate its position with time of receiptinformation. This triangulation is accurate to meters and is highlysuitable for use in navigation for oceanic ships, cars or when walking.However, GPS signals do not provide accuracy to five inches or less aswould be desirable in a Virtual Reality (VR) and Augmented Reality (AR)systems. VR technologies, such as simulate an environment and typicallyprovide a view of this environment on a head mounted display (HMD) whichmay also provide headphones with synthesized sound. AR technologiesprovide images which are partially of actual object with synthesizedcomputer generated images superimposed upon it. VR and AR technologiesare described in U.S. patent application Ser. No. 13/967,058 filed Aug.14, 2013 and Ser. No. 14/614,734 filed Feb. 5, 2015, owned by the ownerof the this application, and are hereby incorporated by reference as ifset forth in their entirety herein.

GPS systems do not work as well indoors. Many indoor tracking systemshave been proposed. Apple iBeacons, for example, use Bluetooth LowEnergy (BLE) transceivers to transmit beacon identification (and other)information and the location of a receiver from the iBeacon iscalculated based on Received Signal Strength Indicator (RSSI). Such asystem is a proximity indicator, and does not provide a high level oflocation accuracy necessary in many modern applications. There have beenother attempts at accurate indoor wireless positioning systems,including for example the IEEE paper “Improving WLAN-Based Indoor MobilePositioning Using Sparsity”, by Pourhomayoun and Fowler (2012). However,to date, such systems have accuracy of about a meter, which is notadequate for real time tracking of position in many applications.

The above tracking systems have multiple uses in gross positiondetermination. However, more recently, the need has arisen for preciselocation and tracking of objects or devices, both indoors and outdoors.Wireless tracking is described more fully in U.S. patent applicationSer. No. 14/600,025 filed Jan. 20, 2015 and Ser. No. 14/354,833 filedApr. 28, 2014, owned by the owner of the this application and are herebyincorporated by reference as if set forth in their entirety in thisapplication. For example, VR and AR technologies are starting to emergeas viable interactive means of communicating, working, playing, andexploring with the digital world. To make these new AR and VR systemsmore effective, the need for improved accuracy and faster response inthese systems increases. These improved systems must contemplate theuser experience from the moment they begin interacting with the AR/VRsystem, thru its use and return to a disconnected world. Such animmersive experience requires precise real time tracking of the user fora realistic experience.

U.S. Pat. No. 8,749,433 issued Jun. 10, 2014, discusses a system fortracking an RF transmitter. If attached to an object, tracking this RFtransmitter will also track the attached object.

This type of tracking has been integrated into a virtual reality systemas discussed in U.S. patent application Ser. No. 14/614,734, filed Feb.5, 2015, owned by the owner of this application, and hereby incorporatedby reference in its entirety herein. In such a system, a transmittertransmits its location, and multiple receiver antennae and a controlleruse time difference of arrival (TDOA) to determine the position of thetransmitting device. This allows the tracking to be precise; however, ifonly one transmitter is utilized, then only one transmitter (point) maybe tracked.

Another technique for internal tracking of objects is described in thepaper “Multifrequency-Based Range Estimation of RFID Tags” (2009, IEEE,by Xin Li). In this paper, multiple frequencies are compared using aphase difference of arrival (PDOA) to locate or track objects. Theradiofrequency identification (RFID) tags employed with the presentsystem include a means for transmitting and receiving RF signals, aprocessor, memory which may include executable code and possiblysensors. The RFID tag can then execute a program and function asdescribed herein.

In this technique, multiple frequencies are transmitted to an RFID,which retransmits the frequencies as is known to those skilled in theart. The returned signal can be used to calculate the distance from thetransmitter to the RFID. However, analysis of the returned signal onlyprovides a distance measurement from the transmitter to the RFID tag.Several tags must be used to determine directionality.

Of particular interest in AR and VR are virtual reality glasses and/orhead mounted displays (“HMDs”). As HMDs become more prevalent, newfunctionality to enable better engagement with and connection to thevirtual world become critical.

There are a variety of approaches that attempt to provide an intuitiveinterface for controlling content shown on these devices—as is criticalto the effectiveness of how HMDs are used. As most of these HMDs will bewireless and mobile, operated away from desks or related environmentswhere computer mouse or trackpads are accessible, there needs to be aneffective solution for providing input control without requiring atypical input device. Cameras can be installed on the HMDs to track aperson's hand gestures and these gestures can then be used forinteraction. But, in these camera-based systems, gesture tracking can belimited by the field of view of the camera, accuracy of the cameragesture tracking, range detection of the hand position as viewed by HMDcameras, or the lack of tactile input to the hand or fingers as they areinteracting with the program running on the HMD.

Most VR/AR systems require recalibration of the tracking system when thenumber of tracked objects changes. This make the systems difficult toproperly configure and impractical for certain uses.

The geographic area in which objects may be tracked is typicallylimited. The objects must be within the transmission range of thetransmitters. Once the objects are outside of this area, they can nolonger be tracked.

Some prior are tracking systems require significant RF transmission thatrequire significant energy to operate. If a user would like tocontinuously track objects, then the amount of power dissipation becomessignificant. This power dissipation reduces battery life.

Barcode readers and mobile scanners are described in U.S. patentapplication Ser. No. 14/568,468 filed Dec. 12, 2014 which is owned bythe owner of this application and hereby incorporated by reference as ifset forth in its entirety herein.

While the above systems for tracking are useful, they do not provide asuitable method of tracking objects with precision and in real time.Furthermore, they do not address real time tracking of multiple objectsin a coordinated way as would be required in an AR or VR environment.Currently there is a need for highly accurate and low power trackingsystems for indoor and outdoor tracking of multiple points on multipleobjects.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the system described in this application will becomemore apparent when read with the exemplary embodiment describedspecification and shown in the drawings. Further, in the accompanyingdrawings and description that follow, like parts are indicatedthroughout the drawings and description with the same referencenumerals, respectively. The figures may not be drawn to scale and theproportions of certain parts have been exaggerated for convenience ofillustration.

FIG. 1 is a schematic illustration of a head-mounted display (HMD) beingtracked by a tracking system according to one embodiment of the presentinvention.

FIG. 2 is a schematic illustration of the major elements of an HMDreceiver according to one embodiment of the present invention.

FIG. 3 illustrates how inaccurate tracking leads to image distortion invirtual reality systems.

FIG. 4 is an illustration of the use of mobile devices to create moreaccurate location determinations.

FIG. 5 illustrates the use of the tracking system implemented in twodifferent automobiles to predict and prevent collisions.

FIG. 6 shows location and orientation determinations for HMD in twodimensions using a single transmitter and two receiving antennae.

FIG. 7 shows location and orientation determinations for the HMD inthree dimensions using a single transmitter and three receiving antennaein different planes.

SUMMARY

An accurate and intuitive approach for interfacing with devices havingRF capabilities, such as HMDs, mobile devices and the like, withoutcamera gesture tracking, can enable new use cases and more effectivecontrol of content shown on these devices. As most HMDs will have radiocommunication capabilities, a means to leverage this functionality toenable interaction is helpful and economical. A method to enable HMDs touse their basic radio communication to accurately track their ownposition as well as the position of input devices in free space canenable better interaction as well as reduce costs.

The HMD would have two or more antennae embedded in or mounted to theHMD. A multifrequency transmitter, such as an Access Point, provides twoor more frequency signals to the two or more HMD antennae. The HMD usesthese two signals as received at each antenna to identify the rangebetween the antenna and the Access Point. Then, using both (for two HMDantennae) ranges from either one or more Access Points with knownposition coordinates and the heading and orientation as supplied byinertial sensors in the HMD, the HMD can determine accurate positioninformation.

Position can be further defined and accuracies improved using RF signalsfrom additional Access Points, transmitters sending locationinformation, motion sensors (including GPS, magnetic, accelerometer,gyroscope) or other position and/or orientation information sources.

The present disclosure also provides the ability for an HMD toaccurately track the relative three-dimensional position of a wirelesstransmitting device such as an RFID device, or such as a phone, ring,wristband, stylus, handheld pointer, or related interactive peripheraldevice, (“Tag”), using the same multifrequency transmitting methoddescribed above for Access Points communicating range to the HMD. Thisrelative position tracking would provide a flexible and intuitiveapproach for HMD interaction. Tags could become intuitive, interactiveperipherals for HMDs and provide a unique and effective means to engagewith programs displayed on the device without requiring a mouse,trackpad, camera, or related input solution.

HMDs can track the position of a Tag and use the position data to engagewith a software program running or displayed on the device. In theseapplications, the Tag position and movement would be registered withscreen images provided by software and shown on the HMD. To make thisTag's operation effective for a user (to control a cursor on a screenfor example), very high position accuracies are required to providerealistic interaction between the user operating the Tag and thesoftware program shown on the HMD. Herein is described a method that canprovide said tracking capability for the HMD to meet the accuracy andcost requirements of these devices but also work with hardwareconstraints inherent in the size and ergonomic restrictions of HMDs.

In one embodiment of the present disclosure there is a system thatallows Mobile Devices such as augmented or virtual reality glasses,robots, drones, handheld communicators (mobile phones) or scanners, orany mobile peripheral (Mobile Device) with radio frequency (RF)communication capability and multiple antennae embedded or attached tothe mobile device, to track other devices that emit electromagnetic orRF signals (Other Devices) relative position to the Mobile Device.Further, when multiple Mobile Devices are present, each can calculateand communicate its own position relative to other devices, and the webof devices can provide a means for more efficiently and accuratelytracking other devices. In addition, the Mobile Device may determine itsactual outdoor or indoor position by utilizing certain stationarydevices (Access Points) with RF communication capability and the abilityto provide the Mobile Device with the Access Points' two orthree-dimensional position coordinates. This position can then berelayed to other Mobile Devices or to a tracking center in certain usecases.

The current invention may be embodied as a system for tracking mobiledevices in real time having a multifrequency transmitter, thetransmitter is adapted to transmit identification and positioninformation of the transceiver. It includes a mobile device having auser display that provides images to a user as viewed from a specifiedviewpoint, at least two mobile display antennae mounted on the displayadapted to receive signals from the multifrequency transmitter, areceiver circuit having a carrier recovery circuit that functions tosynchronize the signals received by each wireless, compare their phasesand determine phase differences; and a processor running coupled to thereceiver circuit, adapted to run executable code. The executable codefunctioning to receive the phase differences from the receiver circuit,calculate the distance from a multifrequency transmitter to each antennabased on phase differences, and calculate the position of each antennabased on the calculated distances, and causing the images provided tothe user to have viewpoint based upon the calculated positions of eachantenna.

The current invention may also be embodied as a system for tracking thelocation of movable objects having a plurality of transceivers beingcapable of Bluetooth, Wi-Fi, cellular and near field communication. Eachtransceiver has a transmitter capable of transmitting an RF signal areceiver capable of receiving an RF signal, a processor capable ofrunning prestored executable code. The executable code, when run causesa requesting transceiver to broadcast a signal requesting nearbytransceivers to transmit a signal back which includes an identifier ofthe transceiver, determine a range from each corresponding transceiver,and calculate, from the plurality of received signals, a location of therequesting transceiver.

The current invention may also be embodied as a method of tracking aposition of a movable objects by providing at least two trackedtransceiver at known locations relative to the tracked object, employinga least two node transceiver which will return a signal when requestedand transmit their identity in the signal, transmitting from the nodetransceivers, and indication of their presence, requesting from thetracked transceivers, that the node transceivers send a reply, receivingat the tracked transceivers the signals from each of the nodetransceivers, determining a distance between the each node transceiverand tracked transceiver, and using the known positional locations of thetracked transceivers to the movable object, and calculating the positionof each tracked transceiver, and the movable object relative to the nodetransceivers.

DETAILED DESCRIPTION

Basic Tracking

FIG. 1 shows a tracking system 100 for tracking a mobile object, such asa mobile display or a head mounted display device (HMD) 300 that has adisplay 309 for each of the user's eyes that is generated by a , and twoor more antennae 301, 303, attached to, or embedded in said HMD 300. Theantennae 301, 303 are designed to be a known, fixed distance apart, anda known fixed distance from each of the displays 309. The HMD 300 mayemploy side arms 305, 307, like those of eyeglasses to hold the HMD 300to the user's head in the proper position. Alternatively, the HMD may beheld in place with straps or other commonly known suitable attachments.

Access points 210, 220 each transmit an RF signal which is sensed bythese antennae 301, 303. In this embodiment, at least one Access Pointis a wireless router. Each Access Point 210, 220 includes sourceidentification in its signal. This allows the source of a receivedsignal to be determined Therefore, antenna 301 receives the first signalfrom the closer Access Point 210, and then receives the second signalfrom farther Access Point 220.

Similarly, antenna 303 receives the signal from the closer Access Point220, and then receives the signal from farther Access Point 210. Thisresults in four received signals.

The signals received from antennae 301, 303 are provided to an HMDreceiver 320 that determines position information. The HMD receivercircuit 320 in this embodiment is built into the HMD 300.

Signals from HMD 300 are provided to an HMD receiver 320. HMD receivercircuit 320 includes a carrier recovery circuit 330 that determines thephase differences between the signals received at the antenna 301 andthat received at 303 for both Access Points 210, 220.

HMD receiver 320 also includes a data processor 339 that computes thedistances between the RFID tag 601 to each of the HMD antennae 301, 303by analyzing signal's phase differences.

The phase offset information from the phase comparator 335 is passed toa data processor 339 which knows the distance between the antennae 301,303 and calculates the relative distance between each of the AP antennae210, 220 and each of the HMD antennae 301, 303. In this embodiment, thedifference in the time of flight (TOF) of the signals is used todetermine relative distances. Additional information is required touniquely identify the position and orientation of the HMD 300.

There is an initial transmission and a return transmission. The initialtransmission in this embodiment described above for FIG. 1 has theAccess Points 210, 220 initially transmitting to antennae 301, and 303which are each connected to a transceiver on HMD 300. Each transceiveron the HMD 300 creates a signal that is broadcast and sensed by theAccess Points 210 and 220. Therefore, Access Point 210 receives a signalbroadcast from antenna 301 and 303. Access Point 220 receives the signalbroadcast from antenna 303 and that broadcast from antenna 303. Thesignal from antenna 301 has an embedded ID indicating that it came fromantenna 301, while the signal from antenna 303 has an ID embedded itwhich identifies that it came from antenna 303. By comparing thetransmitted signal received from each transceiver one can determine thephase offset that indicates the difference in distance the signalstraveled.

In an alternative embodiment, one can measure the total time it tookfrom sending the initial signal to receiving the response(time-of-flight, “TOF”), taking into account how long it takes theresponding transceiver to make a response. The difference in the TOF ofthe signals from Access Point 210 to antenna 301 and 303 indicates therelative difference in these distances. And similarly, the difference inTOF of the signals from Access Point 220 to antennae 301, 303 indicatestheir relative distances.

Even though this was described as the Access Points 210, 220 initiatingthe transmission and then processing the received signal, the situationmay be reversed in which the HMD antennae 301, 303 broadcast an initialsignal which is received by the Access Points 210, 220. These AccessPoints 210, 220 then respond by broadcasting a signal which is receivedby antennae (and their associated transceivers, not shown).

These broadcast signals are then received and processed by electronicsin the HMD 300 to determine the distance of each antennae 301, 303 toeach of the Access Point antennae 211, 221.

t is understood that all equipment required to process the signal anddetermine distances may be present in both the HMD 300 and Access Points210, 220, which also determines the position and orientation of the HMD300 relative to the Access Points 210, 220.

The position and orientation information of the HMD 300 are thenprovided to a VR system (or AR system) 250. This may be by acommunication link which preferably employs the existing transmittersand receivers. A transmitter—receiver device may be referred to as a“transceiver”. The position information is important in defining theviewpoint used to generate the images provided on display 309. VR system250 employs at least one processor 251 coupled to memory 253. Memory haspre-stored executable instructions 255. Memory is also used for storageof other information 257.

Throughout this description, reference will be made to mobile devices,including specifically an HMD 300. For purposes of this disclosure andas described below in more detail, the mobile devices are not limited toan HMD 300, but could be virtual or augmented reality glasses, robots,drones, vehicles, handheld communicators, scanners, or any device withradio frequency (RF) communication capability. Similarly, those ofordinary skill in the art will recognize that the Access Points may beany type or number of devices at known locations transmitting amultifrequency RF signal with coordinate information.

HMD Receiver

FIG. 2 shows an HMD receiver 320 capable of independently processing atleast two channels of signals, one for the signals received by antenna301 and the other for signals received by antenna 303 at the HMD 300. Inthis embodiment, the phase differences of arrival (PDOA) ofmultifrequency signals sent from Access Point 210, 220 to HMD 300 areused to make range measurements through time of arrival calculations. Inthis example, the individual antenna receiver channels of HMD receiver320 independently determine a phase relationship from the multifrequencytransmission(s) sent from each Access Point 210, 220. The phasedifference measurements are then used to determine time of arrival ofthe signals sent from the Access Point as they are received by the HMDantenna, and the time of arrival information is then used to determinethe distances between antennae 301, 303 and Access Points 210, 220.

In one embodiment for determining phase information, each receivechannel of HMD receiver 320 may be comprised of an antenna 301, 303coupled to an amplifier circuit 321 to amplify the received signal.

The amplifier circuit 321 is coupled to a down-converter 323 to bringthe frequency of the signal down to a frequency that can be processed.

Down converter 321 provides the down-converted signal to a filter whichpasses a signal band that is to be processed.

An analog-to-digital converter (ADC) 325 receives the filtered signal,samples the signal, digitizes the samples and provides them as a streamof digital information.

Each Access Point 210, 220 transmits signals with a specific and knownPN code, which is then used by the receiver to de-spread the signal. Adigital signal processor 331 is coupled to the ADC 327 and separates outsignals on multiple frequency bands. This may be done by deconvolutingthe signal with a particular pseudo-noise (PN) sequence code from apseudo noise generator (PN) 329.

The system may employ a delay locked loop (DLL) 243 to synchronize withthe signal. After the synchronization has occurred, parallel digitalfilters may be used to separate out multiple frequency components fromthe signal.

After separating out the frequency components, the phase of eachcomponent is extracted and compared using a differential phasecomparator 335.

Each frequency band may include a separate set of information. Forexample, frequency band Freq_1 may include information relating to thesignal received by HMD antenna 301 which was transmitted from AccessPoint 210. Similarly, Freq_2 could have information relating to thesignal received by HMD antenna 303 which was transmitted from AccessPoint 220.

The digital information on the various frequency bands Freq_1, Freq_2 .. . Freq_N can be used to calculate various times of arrival of thesignals, various distances and ultimately, the relative position andorientation of the tracked object.

The digital processor then utilizes the phase information to calculateseveral ranges and then the location and orientation of the HMD from theranges. One possible technique for calculating range based onmultifrequency phase differences from a single transmission source isdescribed in detail in the above-mentioned paper “Multifrequency-BasedRange Estimation of RFID Tags” (2009, IEEE, by Xin Li), and is herebyincorporated by reference as if set forth in its entirety herein.

The relative position of two antennae, with respect to each other areknown. In FIG. 1, antenna 301, 303 are fixed to the HMD approximately 5inches apart and on a common plane for ease of understanding. Theextracted phases are utilized to determine four distances, being thatbetween each HMD antenna 301, 303 and each Access Point 210, 220. Usingthis information, the relative position and orientation of the HMDantenna 301, 303 relative to the Access Points 210, 220 within a2-dimensional plane can be determined

In this first embodiment of FIG. 1, if the wireless Access Point 210 hasa known absolute location (X,Y,Z, or any other coordinate system) withrespect to a universal coordinate system, the absolute position andlocation within a 2-dimensional plane may be determined This physicallocation is broadcasted as part of, or in addition to, the multiplefrequency RF signal sent from the Access Points 210, 220. Similarly, theother Access Points also may transmit their absolute locations.

The use of a system employing a single Access Point may be acceptable incertain applications. For example, if one only requires to measure adistance from the Access Point 210 to an HMD 300, a single Access Pointwould be adequate. However, it is often desired to precisely determineand track the location and orientation of a mobile device, such as HMD300. In this case, multiple Access Points would be required.

The present system provides improved location accuracy if there are twoAccess Points, as shown in FIG. 1, as opposed to a single Access Point.In such a setup, the HMD 300 uses both antennae 301, 303 to determinethe distance to the two Access Points 210, 220 as described above basedon PDOA information. Each Access Point 210, 220 has a unique PN codethat identifies its RF multifrequency signals. Since the antenna 301,303 have a known spatial separation and the orientation can bedetermined with motion sensors, the position of the HMD 300 can bedetermined

The distance from the Access Points 210, 220 to each HMD antenna 301,303 is calculated using time of arrival information using PDOAinformation from the dual or multi frequency signal transmitted by theAccess Points 210, 220.

In this case, the two-dimensional (2D) position of the HMD 300 cannot bedetermined using only two Access Points 210, 220. Since these determinedistance from the transmitter in any direction, the possible solutionsfor a single distance result in a circle around the transmitter. Whenthis process is repeated for a second Access Point, there are now twosolution circles that intersect at two locations. This results in twopossible solutions. However, once the HMD starts moving, the heading andorientation of the HMD 300 can be utilized to reduce the solution spaceto a single solution and determine the position of the HMD 300.

In order to calculate the orientation of the HMD 300, in addition to its2D position, requires an additional Access Point. Trilateration can beperformed using the known position information of the two Access Points210, 220 and position of the HMD antennae 301, 303 as calculatedrelative to the Access Points 210, 220. For determining 3D positionwithout having motion/orientation sensor information, it is preferred tohave four Access Points 210, 220, etc. to perform multi-lateration andaccurately determine the position of the HMD 300.

Assuming that the location of each wireless Access Point 210, 220, . . .is transmitted to the HMD, the precise location and orientation of theHMD 300 is now calculable. It will be recognized that further AccessPoints providing additional multifrequency RF signals incorporatingtheir known positions will further improve system accuracy andresiliency. For system cost reduction, it may be a desirable designchoice for multiple transmitters to share a single processor thatgenerates the multifrequency RF signals and unique PN identifier codefor each Access Point.

For AR applications, accuracies of less than 5 mm and orientationheadings of less than 0.2 degrees are desired. Otherwise, the objectscoincide depending on the distance of the object to the viewer. If theobject is far away, small orientation errors (<1 degree) will cause theobject to move in respect to its background, and for objects that areclose to the viewer small errors in position (<1 cm.) will cause theobject to move, thus, degrading the AR experience.

To acquire accuracies that are less than a few inches in ARapplications, the system improves accuracy using image processingtechniques that reduce the computational burden by locking an object'sshape and color contrasts. It can also approximate an object's motion inspace. For example, the software can perform smoothing of objectmovement by causing displayed images to move in curves or lines, ratherthan in a jerky or jittery motion. Various other image-processingtechniques can be utilized to improve image presentation.

For example, as seen in FIG. 3, an object, such as a cylinder 5 may sitin front of a mountain 3 (real or virtual). If the cylinder 5 is beingtracked and does not move for a period of time, any motion of the objectdetected when the viewpoint changes, may be rejected or “smoothed” andno object motion would be displayed. The cylinder 5 is thus biased aslocked in place relative to other objects in the image unless motion isrepeatedly verified over time or verified by multiple Access Points.

At system start-up, a Mobile Device, such as HMD 300 in this example,may be put into a precise known position and orientation relative to theAccess Points and the difference between the HMD's calculated positionand known position are determined as the calibration error. The systemis then adjusted to compensate to use the offset error in calculationsto more accurately determine positions.

Motion and orientation sensors may be employed to supplement tracking,as indicated above.

FIG. 4 shows another embodiment of the tracking system according to thepresent disclosure that utilizes a variety of transmitters 210, 230, 240to fix either relative position or absolute position of a trackeddevice, here being HMD 300. The system may adjust to function as severaldifferent embodiments.

First Embodiment

In the embodiment shown in FIG. 4, multifrequency RF signals andlocation information are sent from an Access Point 210 (as describedabove) and a stationary mobile transmitter 230 (such as a cell phone).The HMD 300 uses the phase difference of arrival relationships from themultifrequency signals received from both the Access Point 210 and themobile transmitters 230, 240 to determine the locations of HMD antennae301, 303. In this embodiment, the mobile device transmitter 230 actsmuch like the second Access Point. More specifically stated, once theMobile Device 230 location is identified accurately, it transmitsmultifrequency RF signals and its location to the HMD 300. The distanceinformation from the HMD 300 to the Mobile Devices 230, 240 and AccessPoint 210 are used to accurately determine the HMD's 300 relativeposition. Adding the know position of stationary mobile transmitter 230to the positions relative to mobile device 230 results in absolutepositions.

The location of the Mobile Device 230 may be determined in a variety ofways. Preferably, however, the Mobile Device 230 independentlydetermines its position using phase difference of arrival frommultifrequency signals from the Access Point 210 (or Multiple AccessPoints), such as described above. Alternatively, the location of theMobile Device 230 may be tracked by a networked system by transmitting asignal to a plurality of receivers at fixed locations, such as describedin U.S. Pat. No. 8,493,733.

A receiver would then calculate the PDOA either at each Access Point (ifMobile Device sends multifrequency RF signals) to calculate TOAinformation or by comparing the Mobile Device RF signal's phase at eachAccess Point to calculate time difference of arrival (TDOA) information.In both approaches, distances are used to perform multi-laterationcalculations to determine the position of the Mobile Device and reportit back to the Mobile Device.

Determining mobile device position to an accuracy of a few inches orbetter is needed to enable effective HMD VR or AR functionality. Inaddition to VR and AR functionality, certain applications for HMDs orother mobile devices require high resolution, highly accurate positiontracking functionality. Using phase as a means to extract signal timinginformation for position detection is an effective means to meet theseaccuracy requirements.

Networked Tracking

As will be recognized by one of ordinary skill in the art, eachtransmitter that is being controlled to broadcast a known position usingmultiple frequency RF signals to another device coupled to a devicewhich has decoding capabilities potentially can calculate distancesbetween the receiving device and the transmitter. Then, each mobiledevice, such as a radio-frequency identification (RFID) tag that isrunning software or is otherwise controlled in the proper manner, thathas a known position and is stationary (at least for a period of time)can further serve as a reference point, mimicking the function of anAccess Point, providing position information to other devices thatcommunicate with it. Therefore, by loading the proper software on suchdevices, they can create an evolving mesh network of shared positioninformation that will increase geographic coverage and improve locationaccuracy without requiring additional network hardware such as AccessPoints.

Automobile Position/Direction Determination

The systems described above may be implemented for various uses. Forexample, assume the Access Point 210 in FIG. 5 is in the driver's frontcorner of an automobile (“first car”) 501, and that this automobile isGPS enabled. The automobile 501 has Tags 610, 620 that transmitmultifrequency RF signals and location information from antennae 611,621, consistent with the description above.

A driver in a second car 503 may be wearing an HMD 300 with HMDantennae, or alternatively, may have antennae 301, 303 attached tovarious parts of the automobile. In this embodiment, they are at thedriver's front corner, and the passenger's rear corner of the automobile503. These multiple antennae 301, 303 are coupled to a processor (notshown) running executable code that perform the tracking functions asdescribed herein. Transceivers connected to antennae 301, 303 receivethe multifrequency RF signals transmitted from Tags 610, 620 andtransmit signals back to antennae 611, 621. The attached processor incar 501 calculates position and location information based on Time ofArrival information and multi-lateration calculations.

Based on this position information from the second car 503, the systemof the first car 501 may determine the speed and projected path of thesecond car 503. A warning may be issued to the drivers, or in aself-driving or driver-assisted car having a control computer, thecomputer control, either, or both cars 501, 503 may take evasivemeasures (braking, turning, etc.) to avoid a collision. It is understoodthat the situation may be reversed in which the functions described asbeing performed by automobile 501 may be performed by automobile 503 andvice versa. This embodiment functions in a manner similar to thatdescribed in FIG. 6, assuming that FIG. 6 employed two Tags.

It should be recognized that GPS is not the only way to augment thetracking system of the present disclosure. For example, an automobilewill commonly include a compass, speedometer, accelerometers and camerasor other sensing devices (radar). These devices may augment the presentsystem of object tracking. For example, a compass and speedometergenerally provide bearing and speed. However, driver input may changeradically or a car may be moving out of control (i.e., speed and compassare not accurate in a car spinning on ice). In such situations, thepresent disclosure can augment relative tracking between two or morecars. A second car will have two antennae, and the actual motion of afirst car that is transmitting multifrequency signals can be tracked andused to determine if the first car is out of control, getting too closeto the first care, etc.

The above descriptions of tracking HMDs is much more broadly applicablewhen considering that many mobile transmitters and receivers may utilizethe present disclosure. For example, the mobile telephone is ubiquitousin the world today, and in the present disclosure, each mobile phone mayprovide location and tracking services not only to HMDs, but to anyother transmitter including other mobile phones, automobiles, scanners,Access Points, etc. Thus, phone-to-phone, car-to-car, phone-to-car areall links that may provide mutual location and tracking services toimprove the user experience.

Granularity of Information

In the above embodiments, different aspects of position knowledge arerequired. Specifically, for an HMD in a virtual reality system, thelatency delay in tracking is preferably less than 20 milliseconds. Suchcan be achieved with a conventional digital signal processor and limitedfiltering of data.

On the other hand, in the automobile example, location may be determinedon a less fine scale and the system may use longer wavelength RF signalsthat provide greater geographic range, but require larger antennae andresult in slower processing speeds. These choices are within the domainof the system designer knowing the utilization parameters (i.e., speedof objects being tracked, tracking accuracy requirement, etc.).

In certain embodiments of the present disclosure, it is important todetermine absolute physical location (x,y, or x,y,z position in thephysical world). Absolute physical locations are typically identifiedwith respect to a commonly accepted, or a universal reference frame.However, in other embodiments of the disclosure, relative physicallocation is adequate.

FIG. 6 provides another preferred embodiment that does not requiredetermination of the absolute location of the devices, but can functionwith relative locations. In this embodiment, a receiving device, such asan HMD 300, determines the position, relative to itself, of othertransmitting devices, such as an RFID tag 600 that is capable oftransmitting dual or multifrequency radio signal information through itsRFID antenna 601.

Signals from HMD 300 are provided to an HMD receiver 320. HMD receiver320 passes the signals to a carrier recovery circuit 241 that mayinclude a DLL circuit 241 and a phase comparator 243 that determines thephase differences between the received signals. Receiver circuit 240passes the phase difference to a processor 245 that computes thedistances between the RFID tag 601 to each of the HMD antennae 301, 303.

This calculation is described above with relation to the HMD calculatingits 2-D position relative to the RFID tag 600. In such a system, itwould not be possible to determine HMD's 300 absolute position from RFIDtag 600 that has unknown positions.

FIG. 7 shows a simple configuration for determining the relativethree-dimensional position of an RFID tag 600 relative to the HMD 300.In this embodiment, RFID tag 600 transmits a dual or multifrequencysignal and an identification code that is received by at least three HMDantennae 301, 303, 311 placed on or embedded in the HMD 300. These HMDantennae 301, 303, 311 could be placed at the end pieces of the HMD.

In this embodiment, one HMD antenna would compare the phase differenceof arrival of the Tags' dual-frequency signal as it is received at eachHMD antennae. This received dual-frequency signal phase differenceinformation sent from the RFID tag 600 and received at the individualHMD antennae 301, 303, 311 are then used to determine distances betweenthe RFID tag 600 and each HMD antenna 301, 303, 311. The three distancesas determined between each HMD antenna 301, 303, 311 and the RFID tag600 as well as the antennae's known relative separation from each otherand positions on the HMD 300 allows the system, through trilateration ormultilateration techniques, to determine the locations of the three HMDantennae 301, 303, 311 relative to the RFID tag 600. These three pointsdefine a plane which defines the position and orientation of the HMD 300in space.

To improve tracking of the relative position of the Tag, motion sensorsthat may be inside or on the Tag could be utilized to determine theTag's orientation and acceleration, and then combined with rangedetermined by RF.

The system in FIG. 7 may be utilized with or without knowledge of theexact position of the HMD. In the latter case, the position of thesingle or multiple RFID tags 600 that are tracked by the HMD 300 may allonly be related to the HMD 300. This allows full functionality in avirtual reality environment where HMD 300 and/or RFID tag 600 absoluteposition detection is not required.

Alternatively, the position of the HMD 300 may be tracked such as isdescribed above with the use of Access Points 210, 220 . . . , and therelative position of the RFID tags 600 may also be derived based ontheir relative location to the HMD 300. This is more beneficial in anaugmented reality system.

Referring back now to FIG. 1, the HMD 300 is fed information from asoftware program executing in a VR system 250. The software program maybe running locally (i.e., at or near the HMD 300) or may be streamed tothe HMD 300 from a more distant server/processor, such as VR system 250.The software provides images onto the displays 309 viewed by a userthrough the HMD 300. In an alternative embodiment, the images may beviewed on the screen of a mobile device.

In the present disclosure, an RFID tag may be attached to the user'shand (or on an object held by the user). Such an RFID tag may berepresented in a virtual environment generated by the software as acursor, ball, weapon or other object. Motion of the hand causes motionof the RFID tag. The HMD 300 tracks motion of the RFID tag 600 and themovement of the Tag is provided to the software providing images to theHMD 300. Thus, the software shows accurate movement of the cursor, ball,weapon, or other object representing the RFID tag 600 on the HMD 300.The RFID tag 600 may also include motion/orientation sensors thatprovide information to the HMD 300 (along with multifrequency signalsand Pseudo Noise information) for further improving position accuracyand intuitive interaction by adding orientation sensing with multipledegrees of freedom beyond the positional tracking.

In addition, or alternatively, position information may be displayed ifthe relative location of RFID tags on a user is known. For example, iftwo tags were placed on a user's hand, such as one tag on a thumb andone on a pinkie finger, hand orientation may be displayed in a virtualreality environment based on the position of the two tags relative toeach other.

In the particular application of the present disclosure that relates toglasses or an HMD type device, further uses are created by the presentdisclosure. For example, glasses and HMDs often have earbuds or thelike. If the location and orientation of the HMD are determined in anaugmented or virtual reality system, the user can be cued by auditory orvisual input to tum and look in a particular direction. As a specificexample, a user wearing virtual reality glasses driving a car (real orvirtual) may be looking forward as determined by the HMD orientation.Detecting this orientation, the augmented or virtual reality program mayinstruct the user through the earbud (or by visual cue) to “look left atan object” and then provide the appropriate vision for the user as theHMD is tracked to move left. Similarly, the system can track virtualreality objects and provide sensory feedback to the user based on theirlocation. For example, if the user fails to move as determined by theHMD tracker, a buzzer on a part of their body could provide feedbackthat a virtual ball has “hit” the user.

The above embodiment is broadly described relative to augmented orvirtual reality systems, and it might be thought limited to veryconstrained environments. However, the above system can be integratedwith other technology. For example, it is recognized that GPS locationdoes not provide the required accuracy in many environments, andespecially indoor environments. However, each GPS may transmit andreceive RF signals on multiple frequencies and position information tofurther expand the mesh network of location tracking devices describedabove. Alternatively, an RFID tag 600 may be connected to a GPS unit (anHMD or drone, for example). In this situation, the location andorientation of the HMD may be added to the location of each GPS unit toprovide more accurate location information.

While the absolute position accuracy of the HMD as determined by the GPSunit is less precise than AR or other HMD applications with highaccuracy requirements, in certain use cases, such as the case oftracking multiple automobiles described above, this precision may proveadequate. Triangulation of increasing number of GPS-enabled HMDs orsimilar Mobile Devices could improve absolute location accuracy. In thissituation, for example, one precise position location may be derivedfrom an Access Point, and may be communicated to other Mobile Devices.This will greatly improve the entire system's Mobile Device positiondetection.

More specifically, turning back to FIG. 4, three devices areillustrated: an Access Point 210, two Mobile Devices 230, 240, and anHMD 300. However, as mentioned above with respect to cars, at differenttimes each device may act as a device being tracked or as a trackingdevice, provided a device has multiple antennae (or an extensionproviding multiple antennae) when it is being tracked, the ability toemit multifrequency RF signals, and is running the appropriate softwarewhen tracking another device.

For example, in FIG. 4 assume that the Access Point 210 is a Mobilephone that has location information (from GPS, user input, a local areanetwork or other source). The Mobile Phone transmits multifrequency RFsignals to a second Mobile Device that has multiple antennae anddetermines its location as described above. The HMD 300 may be a thirdMobile Device, which also receives the multifrequency RF signal from theMobile phone and likewise determines its location. In this embodiment,the additional information is the relative location of the second andthird Mobile Devices as determined using the signal from the Mobilephone.

The above system can be improved for accuracy when each Mobile Deviceaugments the calculated position information with otherlocation/orientation information. Thus, if each Mobile Device includes aGPS, the tracking information may be augmented by sharing GPS locatorsamong the three Mobile Devices. This may allow less frequenttransmission of multifrequency signals for location tracking to conservebattery power if the tracking application requires less exact positioncertitude.

Dealing with ‘Bad Data’

It should be noted that with mobile devices, position and orientationwill change with user movement. Further, a mobile device (or even anAccess Point) may be broadcasting “bad” position data either thruerroneous calculation or for nefarious reasons. There are multiple waysto address such concerns.

In the case of mobile devices, the mobile device will typically containmultiple options for determining gross or accurate position. GPS canprovide gross position information, while the above referenced phasedetermined TOA or TDOA based position calculation systems provide muchfiner position, and even orientation, detail. Phones often includeaccelerometers, gyroscopes, and magnetic sensors that may also indicatemovement of the mobile device. The central processing unit may beprogrammed to, for example, cease broadcast of position information ifthe accelerometer detects movement and the position of that device isunknown due to the movement. Alternatively, one could rely on positionmovement relative to GPS coordinates to terminate transmission ofposition information, or a combination of factors may lead toterminating position transmission due to suspected errors. The presentdisclosure contemplates weighing input from multiple sources todetermine if position calculated is accurate. The weight given aposition calculation may depend on the perceived credibility of theinformation source. For example, if a GPS signal indicates a grossposition miscalculation and only one Access Point is available, thedevice may reject the Access Point information. Alternatively, ifmultiple trusted Access Points are designated as trusted positionproviders and are consistent in their location calculation, but GPSsignal is weak or sporadic (indoors for example) the system may rejectGPS information entirely.

On the receiving side when determining position location, it is harderto discriminate bad data. However, incorporating RF multifrequencysignals and location information from multiple transmitters can provideredundancy for multiple position data points to determine best fits inpredictive models and I or for screening position data not correlated toknown system transmitter coordinates. One could also append “trustedsource” tags to data position so that a user could elect to only usecertain RF transmitters when calculating their absolute position.

The present disclosure may incorporate a variety of possible alternativetechnologies and be used in a broad range of applications. For example,with respect to an inventory tracking system, there are a plurality ofobjects being tracked, including but not limited to palettes, crates,robots, scanners, people, cartons, boxes, trucks, etc. Some or all ofthese objects may include location-tracking capability along withidentification ability.

Package Tracking

The RF tracking may utilize, for example, a scanner (Scanner or Reader)to identify and track objects as described in U.S. patent applicationSer. No. 14/568,468, filed Dec. 12, 2014, titled “Tracking System withMobile Reader”, the entirety of which is incorporated by referenceherein. Objects can be identified and the location of the objectassociated with the Scanner's determined position. In such a system, thepresent disclosure may utilize any identification means like RFID,barcode, etc. The Scanner may, in one embodiment, be an ultra-widebandsystem that reads ultra-wide transmitters or transceivers placed onboxes and packages. In such an embodiment, three or four ultra-widebandtransceivers may be fixed in at least 3 locations within a packagestorage area, which may be a cargo area, or a package delivery vehicle.Preferably these locations are in the corners, but may be at othersuitably spaced locations.

Each package in the truck with a transmitter or transceiver is uniquelyidentified and located as detailed above by the antennae in the truck. AGPS is typically available in such vehicles and the GPS may beinterfaced to the tracking system. Thus, when the driver arrives at ahouse/business, the GPS identifies the address and specifies thepackages that are to be delivered. The tracking system can determine thelocation in the vehicle of the objects to be delivered to that addressand provide the location of the packages to the driver, thus speeding updelivery. Further, if multiple packages are to be delivered, but thetracking system identifies that only one object is removed from thevehicle, the driver can be notified that another package remains in thevehicle to be delivered to the GPS identified address. This type ofgeo-fence will greatly improve delivery efficiencies.

Since the transceivers transmit over a transmission region larger thanthe delivery truck, the system may also track the package as it is beingcarried outside of the delivery truck, but still within the transmissionrange.

The present disclosure may incorporate a variety of possible alternativetechnologies and may be used in a broad range of applications. Each ofthe objects being tracked may include location tracking capability alongwith identification or information storage ability. Each object may beidentified and the location of the object associated with a Scanneridentifying the object. Such a system may utilize any identification orinformation storage means like RFID, barcode, etc., within the scope ofthe disclosure.

In such a system, the Scanner may determine the position of objectsrelative to itself (as in the delivery truck example) and can determineits position using one or more antenna mounted on the Scanner and usingmultifrequency, ultra-wideband, or similar RF signal transmissions toand/or from one or more Access Points with known position coordinates,as described above with relation to the HMD, and/or with otherintegrated location identifiers (i.e., GPS). The Scanner can readinformation from RFID, as well as provide location information to theRFID(s). Thus, it will be noted that, similar to the above descriptionof a HMD or GPS, once a Scanner has calculated its position, it maytransmit RF signals or other means to deliver data with identifierinformation and its physical location. Other devices receiving thesesignals may now calculate their own physical position using the Scannerand other objects' or Access Points' position data.

In an alternative embodiment, an object may need power to provide asignal indicating its location. In which case one could provide power tothe device by immersing it in a wireless power field (i.e., MagneticResonance, Inductive, time-changing magnetic field, etc.). In such anembodiment, when a device (such as a package) enters a power field, theelectronics in the package can ‘power up’ and then communicate withother devices and/or a host system using the same transmittingtechniques described in this disclosure.

In one embodiment, a Scanner is utilized to record and store objectinformation and location at which the product was scanned, as shown inabove referenced in U.S. patent application Ser. No. 14/568,468. Thatobject will transition through a plurality of facilities such asmanufacturing, processing, storage, transportation and retail. Each timethe product is scanned, the object information and scan location areread as described in the cited application. However, as shown in FIG. 2,if the package has the proper circuitry to respond to a wireless powerfield, as the package passes a power field, the electronics on thepackage (that provide the package's identification and relatedinformation) could receive power and transmit the information and/ortheir location.

In one such embodiment, a package of a perishable material has an RFIDchip on it that records temperature. Such are sold byAlienTechnology.com or Zebra.com. When placed in range of a wirelesstransmitter sending multifrequency signals, the RFID can power up,record the temperature and transmit this information. Note that somesystems are battery powered for automated, intermittent temperaturerecording. In such a system, all recorded temperatures may betransmitted by the RFID on power up. In such a system, any wirelessreceiver in range of the RFID tag now has two pieces of information: therecorded temperature and a general location of the RFID device. In somesystems, this may be adequate, but in a preferred embodiment, thelocation of the RFID tag would be determined as described above by usingmultiple receivers to tri laterate or triangulate the tag position. Oneof ordinary skill in the art will recognize that although RFID andbarcode technology are commonly used today to store item identificationand/or information, other technologies or protocols for data storage andtransmission may be used in the present disclosure.

One of ordinary skill in the art will recognize that the relative fixedlocations of the antenna in a device is within the discretion of thesystem designer. For example, in the HMD example provided above theantennae were stated to be placed 5 inches apart on a plane. In thetruck example, the antennae were placed in corners of the vehicle cargobay. However, the distance and location can be chosen by the designer tooptimize the ability of the objects to be located and/or to furthertrack other transmitting devices (Tags, RFID, etc.).

One of ordinary skill in the art will recognize that a variety ofwireless transmitters and receivers may be used in the presentdisclosure. For example, the position of the HMD may be determinedrelative to transmitted RF signals using varying combinations of tags,mobile devices or fixed devices (routers, hubs, Access Points, etc.)using a variety of communication protocols (Bluetooth, 802.XX, WLAN,ultra-wideband (UWB) and others).

In one embodiment, connecting two or more of the receiver antennae to asingle receiver channel provides a major cost savings in hardware andlimits circuit board space required by an HMD. In this example, onereceiver channel would be used for both receiver antennae on the HMD. Toenable this function, we employ a multiplexing technique that will allowthe receiver channel to multiplex between each HMD antenna afterextracting the PDOA data from the signals sent from the Access Pointscommunicating with each antenna. To accomplish this multiplexingfeature, our single (for both antennae) receiver channel would alsoinclude a multiplexing switch (MUX), connected to each of the HMDantennae through an electrical connection that will toggle between eachantenna.

In an alternative embodiment, there are several nodes set up in spacedlocations throughout a building, such as their office or home in whichthe nodes know their locations. There are several devices which areportable that have the logic of the current invention built into them.These may be tablets, laptops, smartphones and other mobile computingdevices which are capable of Wi-Fi, cellular, and Bluetooth, RFID andnear-field communications. The current invention may use any of thesecommunication modes as long as the receivers are also capable ofreceiving these communication modes.

Therefore, the system may have nodes set up to periodically listen forcommunications from different transmitting devices in an area, such asthe building. The nodes then interact with that portable device and withother local nodes to determine the location of the portable device. Theyalso acquire the ID of the portable device and transmit the informationalong with a time stamp, node to node to an uplink node, through anetwork to a server where the information is stored in a table. If theportable device is picked up and moved, the system performs the samefunctions and updates its locations and time stamp in the table. Thistherefore keeps the last known location of portable devices along withthe timestamp.

A user will set up multiple devices this way, such as the laptop,cellphone, tablet, etc. Also, for objects which do not have a built-intransmitter/receiver, a tag can be attached to it, or built into it. Forexample, the user's keys may have a tag and a unique ID; his wallet canhave a tag and unique ID, etc. The user can then look to the table onthe server and find the last known location of all of his objects.

In an alternative embodiment, there are several portable objects lyingaround at various locations in the building within the range of a numberof nodes. Think of these as your cellphone, wallet, laptop, keys, etc.These portable objects either have the capability to transmit andreceive in several of the communication modes described above, or have atag attached to them that has these capabilities. If the portable objectis within an area to contact at least 4 other transmitters, one of whichknows its location, the portable device can determine its location.

A user has a wearable device, or a tag with similar capabilitiesattached to him/her. As the user moves around the building, the attachedtag listens for transmissions from the portable devices, communicateswith them to acquire their ID and location. If the portable device isnot within an area to determine its location, it may use the tag on theuser to determine its location. The information may then be passed backto an Uplink Node, network and server to be stored.

In an alternative embodiment, the user's tag may be the device whichstores the location, timestamp and ID of all portable objects so italways has the last known location of all portable devices.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method, and computer programproduct. Thus, aspects of the present invention may be embodied entirelyin hardware, entirely in software (including, but not limited to,firmware, program code, resident software, microcode), or in acombination of hardware and software. All such embodiments may generallybe referred to herein as a circuit, a module, or a system. In addition,aspects of the present invention may be in the form of a computerprogram product embodied in one or more computer readable media havingcomputer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. The computer readablemedium may be a non- transitory computer readable storage medium,examples of which include, but are not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination thereof.

As used herein, a computer readable storage medium may be any tangiblemedium that can contain or store a program for use by or in connectionwith an instruction execution system, apparatus, device, computer,computing system, computer system, or any programmable machine or devicethat inputs, processes, and outputs instructions, commands, or data. Anon-exhaustive list of specific examples of a computer readable storagemedium include an electrical connection having one or more wires, aportable computer diskette, a floppy disk, a hard disk, a random accessmemory (RAM), a read-only memory (ROM), a USB flash drive, annon-volatile RAM (NVRAM or NOVRAM), an erasable programmable read-onlymemory (EPROM or Flash memory), a flash memory card, an electricallyerasable programmable read-only memory (EEPROM), an optical fiber, aportable compact disc read-only memory (CD- ROM), a DVD-ROM, an opticalstorage device, a magnetic storage device, or any suitable combinationthereof.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device. As used herein, acomputer readable storage medium is not a computer readable propagatingsignal medium or a propagated signal.

Program code may be embodied as computer-readable instructions stored onor in a computer readable storage medium as, for example, source code,object code, interpretive code, executable code, or combinationsthereof. Any standard or proprietary, programming or interpretivelanguage can be used to produce the computer-executable instructions.Examples of such languages include C, C++, Pascal, JAVA, BASIC,Smalltalk, Visual Basic, and Visual C++.

Transmission of program code embodied on a computer readable medium canoccur using any appropriate medium including, but not limited to,wireless, wired, optical fiber cable, radio frequency (RF), or anysuitable combination thereof.

The program code may execute entirely on a user's device, partly on theuser's device, as a stand-alone software package, partly on the user'sdevice and partly on a remote computer or entirely on a remote computeror server. Any such remote computer may be connected to the user'sdevice through any type of network, including a local area network (LAN)or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider).

Additionally, the methods of this invention can be implemented on aspecial purpose computer, a programmed microprocessor or microcontrollerand peripheral integrated circuit element(s), an ASIC or otherintegrated circuit, a digital signal processor, a hard-wired electronicor logic circuit such as discrete element circuit, a programmable logicdevice such as PLD, PLA, FPGA, PAL, or the like. In general, any devicecapable of implementing a state machine that is in turn capable ofimplementing the proposed methods herein can be used to implement theprinciples of this invention.

Furthermore, the disclosed methods may be readily implemented insoftware using object or object-oriented software developmentenvironments that provide portable source code that can be used on avariety of computer or workstation platforms. Alternatively, thedisclosed system may be implemented partially or fully in hardware usingstandard logic circuits or a VLSI design. Whether software or hardwareis used to implement the systems in accordance with this invention isdependent on the speed and/or efficiency requirements of the system, theparticular function, and the particular software or hardware systems ormicroprocessor or microcomputer systems being utilized. The methodsillustrated herein however can be readily implemented in hardware and/orsoftware using any known or later developed systems or structures,devices and/or software by those of ordinary skill in the applicable artfrom the functional description provided herein and with a general basicknowledge of the computer and image processing arts.

Moreover, the disclosed methods may be readily implemented in softwareexecuted on programmed general-purpose computer, a special purposecomputer, a microprocessor, or the like. In these instances, the systemsand methods of this invention may be implemented as program embedded onpersonal computer such as JAVA® or CGI script, as a resource residing ona server or graphics workstation, as a plug-in, or the like. The systemmay also be implemented by physically incorporating the system andmethod into a software and/or hardware system.

While the aforementioned principles have been described in conjunctionwith a number of embodiments, it is evident that many alternatives,modifications and variations would be or are apparent to those ofordinary skill in the applicable arts. Accordingly, it is intended toembrace all such alternatives, modifications, equivalents, andvariations that are within the spirit and scope of this invention.

What is claimed is:
 1. A system for tracking mobile devices in real timecomprising: a multifrequency transmitter, said transmitter transmittingidentification and position information of the transmitter, a mobiledevice comprising: a user display that provides images to a user asviewed from a specified viewpoint, at least two mobile display antennaemounted on the display adapted to receive signals from themultifrequency transmitter; a receiver circuit having a carrier recoverycircuit that functions to synchronize the signals received by eachwireless, compare their phases and determine phase differences; and aprocessor running coupled to the receiver circuit, adapted to runexecutable code to: receive the phase differences from the receivercircuit; calculate the distance from a multifrequency transmitter toeach antenna based on phase differences; and calculate the position ofeach antenna based on the calculated distances, and causing the imagesprovided to the user to have viewpoint based upon the calculatedpositions of each antenna.
 2. The system of claim 1, wherein the carrierrecovery circuit comprises: a delay locked loop; and a phase comparatorfor determining a phase difference of the signals received by eachantenna.
 3. The system of claim 1, wherein the receiver circuitcomprises: an amplifier circuit; a down-converter; and ananalog-to-digital converter (ADC), that samples the signal into digitaldata and sends the digital data to a processor.
 4. The system of claim1, wherein the processor runs executable code to de-spread the signalusing a particular pseudo-noise (PN) sequence code.
 5. The system ofclaim 1, wherein the processor utilizes parallel digital filters toseparate the multi frequency components of the received signal into aplurality of separated signals to determine the phase of at least twoseparated signals and compare them using a differential phasecomparator.
 6. The system of claim 1, further comprising: a secondmultifrequency RF transmitter, wherein the mobile device calculates theposition of the second RF multifrequency transmitter based on phasedifference of arrival of the multifrequency signals received at themobile display antennae and the known separation of the mobile displayantennae.
 7. The system of claim 6 of the previous claim wherein thesecond transmitter is an RFID transmitter that receives and retransmitsmultifrequency signals from the display.
 8. The system of claim 7,wherein the transmitter and display receiver utilize ultra-widebandcommunication to determine time of arrival for distances between thetransmitter and mobile display antennae.
 9. A system for tracking thelocation of movable objects comprising: a plurality of transceiversbeing one of the group consisting of: Bluetooth, Wi-Fi, cellular andnear field transceivers, each transceiver having: a transmitter capableof transmitting an RF signal; and a receiver capable of receiving an RFsignal; a processor capable of running prestored executable code causinga requesting transceiver to: broadcast a signal requesting nearbytransceivers to transmit a signal back which includes an identifier ofthe transceiver; determine a range from each corresponding transceiver;calculate, from the plurality of received signals, a location of therequesting transceiver.
 10. The system of claim 9 wherein: the rangefrom the transceiver is calculated from the round-trip travel time ofthe signals received from that transceiver.
 11. The system of claim 9wherein: at least some of the transceivers are stationary, are referredto as nodes, and have a predetermined known location.
 12. The system ofclaim 10 wherein: at least some of the transceivers are not stationary,are referred to as mobile transceivers and calculate their locations.13. The system of claim 12 wherein: a mobile transceiver is carried byeach of at least two automobiles, the mobile transceivers cancommunicate with each other and each processor has additional executablecode that causes it to: identify the locations of the automobiles overtime; and determine if there will be a collision between theautomobiles.
 14. The system of claim 13 wherein: the mobile transceiversare coupled to the automobile instrumentation so that they can use theinformation from the instrumentation in their determinations.
 15. Thesystem of claim 14 wherein: the instrumentation is a GPS receiver, andthe information represents the global position of the automobile, whichis used to determine the absolute position of the transceivers.
 16. Thesystem of claim 12 wherein the nodes are within a package storage area;and the mobile transceivers are attached to packages to be delivered;and there is additional executable code causing the processor to:identify the location of a package within the package storage area. 17.The system of claim 16 wherein the cargo area is within a deliverytruck, and the system further comprises: a GPS device coupled to theprocessor, and the executable code further includes code to: notify theuser when the truck is nearing a location to deliver a package; andidentifies where the package is located in the cargo area.
 18. A methodof tracking a position of a movable objects comprising the steps of:providing at least two tracked transceiver at known locations relativeto the tracked object; employing a least two node transceiver which willreturn a signal when requested and transmit their identity in thesignal; transmitting from the node transceivers, and indication of theirpresence; requesting from the tracked transceivers, that the nodetransceivers send a reply; receiving at the tracked transceivers thesignals from each of the node transceivers; determining a distancebetween the each node transceiver and tracked transceiver; using theknown positional locations of the tracked transceivers to the movableobject, and calculating the position of each tracked transceiver, andthe movable object relative to the node transceivers.
 19. The method ofclaim 1 wherein: the transceivers transmit and receive at least one ofthe modalities being Wi-Fi, cellular, near-field, and Bluetooth.
 20. Themethod of claim 1 wherein: the at least two node transceivers is fournode transceivers in at least two spatial planes and an orientation ofthe moveable object is also calculated.